import Vue from 'vue';
 
// v-dialogDrag: 弹窗拖拽属性
Vue.directive('draggable', {
  bind(el, binding, vnode, oldVnode) {
    console.log(binding, vnode, oldVnode);
    const dialogHeaderEl = el.querySelector('.el-dialog__header');
    const dragDom = el.querySelector('.el-dialog');
 
    dialogHeaderEl.style.cssText += ';cursor:pointer;';
    dragDom.style.cssText += ';top:0px;';
 
    // 获取原有属性 ie dom元素.currentStyle 火狐谷歌 window.getComputedStyle(dom元素, null);
    const sty = (() => {
      if (window.document.currentStyle) {
        return (dom, attr) => dom.currentStyle[attr];
      }
      return (dom, attr) => getComputedStyle(dom, false)[attr];
    })();
 
    dialogHeaderEl.onmousedown = (e) => {
      if (dragDom.classList.contains('is-fullscreen')) {
        // 全屏状态禁止拖拽
        return
      }
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft;
      const disY = e.clientY - dialogHeaderEl.offsetTop;
 
      const screenWidth = document.body.clientWidth; // body当前宽度
      const screenHeight = document.documentElement.clientHeight; // 可见区域高度(应为body高度，可某些环境下无法获取)
 
      const dragDomWidth = dragDom.offsetWidth; // 对话框宽度
      const dragDomheight = dragDom.offsetHeight; // 对话框高度
 
      const minDragDomLeft = dragDom.offsetLeft;
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth;
 
      const minDragDomTop = dragDom.offsetTop;
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomheight;
 
      // 获取到的值带px 正则匹配替换
      let styL = sty(dragDom, 'left');
      let styT = sty(dragDom, 'top');
 
      // 注意在ie中 第一次获取到的值为组件自带50% 移动之后赋值为px
      if (styL.includes('%')) {
        // eslint-disable-next-line no-useless-escape
        styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100);
        // eslint-disable-next-line no-useless-escape
        styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100);
      } else {
        styL = +styL.replace(/\px/g, '');
        styT = +styT.replace(/\px/g, '');
      }
 
      // eslint-disable-next-line func-names
      document.onmousemove = function (dom) {
        // 通过事件委托，计算移动的距离
        let left = dom.clientX - disX;
        let top = dom.clientY - disY;
 
        // 边界处理
        if (-left > minDragDomLeft) {
          left = -minDragDomLeft;
        } else if (left > maxDragDomLeft) {
          left = maxDragDomLeft;
        }
 
        if (-top > minDragDomTop) {
          top = -minDragDomTop;
        } else if (top > maxDragDomTop) {
          top = maxDragDomTop;
        }
 
        // 移动当前元素
        dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`;
      };
 
      // eslint-disable-next-line func-names
      document.onmouseup = function () {
        document.onmousemove = null;
        document.onmouseup = null;
      };
    };
  },
});